The detent hold and release mechanism of the present invention is utilized on a manually positioned controller which provides varying electrical signals to an electrohydraulic proportional control valve system of the type illustrated in assignee's U.S. Pat. No. 4,201,116. In systems of this nature, a conventional hydraulic control valve is hydraulically positioned by a small double-acting servo cylinder which in turn is controlled by a pilot valve actuated electrically through a double-acting solenoid. The solenoid transmits varying forces to the four-way pilot valve which in turn controls the position of the double-acting cylinder. The amount of DC voltage supplied to the solenoid is controlled by the manually positioned controller of the present invention. The controller includes a manually positioned potentiometer or rheostat which in turn is mechanically connected to the detent hold and release mechanism of the present invention.
The rotary movement of the controller handle, which is positioned by the operator, includes a detented position which causes an electrical signal of a certain voltage at the solenoid to apply a certain force against the servo valve which in turn permits fluid pressure to reposition the double-acting cylinder and in turn position the main control valve to a set operating position (all of which is described in detail in U.S. Pat. No. 4,201,116). The operating position might be a normal power-up or down position, float position or a regeneration position depending on the requirements of the particular system.
In the prior art, the detent mechanism is normally a spring-biased mechanical holding structure released by fluid pressure, as shown in U.S. Pat. No. 3,153,949, or by a solenoid, as shown in U.S. Pat. No. 3,790,129.